1. Field of the Invention.
The field of art to which the invention is most likely to pertain is in a class directed or generally related to the fabrication of articles of manufacture having hollow shapes and configurations and made from reinforced fibrous materials.
2. Problems in the Prior Art.
In present practices for making complex configured hollow laminates, difficulty arises in obtaining proper distribution of pressure to and across the entire (basic and built-up portions) laminate during the lay-up and curing steps of manufacture of the article. The built-up portions are required to be added in secondary stages, the basic-lay-up of laminate and the curing and pressurizing of it being considered a single stage process. Furthermore, the present-day time-consuming and expensive procedures (processes, materials andd apparatuses) do not lend themselves to an efficient and maximum use of new materials, examples of which are graphite and boron fibers.
This invention overcomes the many manufacturing problems inherent in present-day practice and techniques utilized in the manufacture of these complex configured laminates by reducing the manufacturing process to a single stage as well as providing a tooling system in which a required curing pressure can be applied to the entire laid-up laminate.
This invention also overcomes disadvantages which have become apparent in the manufacture of an excellent three-dimensional oriented space frame composite structure, named Tetra-Core, developed at the Eustis Directorate of the United States Army Air Mobility Research and Development Laboratory. For example, in this invention wall thickness is accurately controlled and the resin is restrained during the curing step, rather than being allowed to flow.